Condition Was Long Believed More Prevalent Among White Children in U.S.

Researchers have long thought that autism was more common among white children in the U.S. than other ethnic or racial groups. But a new study of birth records in highly diverse Los Angeles County suggests that children whose mothers emigrated from certain countries may be particularly at risk.

Children of foreign-born mothers who are black, Central or South American, Vietnamese or Filipino were more likely to be diagnosed with...